Aids to navigation (ATONs) other than anchored buoys are mounted on piles that are set into the mud or other bottom of a river, etc. in order to mark the channel or obstructions on the bottom. In places where the channel is wide, they are usually not struck by passing marine traffic. However, in places where the channel is narrow or where the traffic is dense they get struck quite frequently. If the pile is rigid and the striking vessel is large; the pile gets snapped off. If the striking vessel is small, or the pile is flexible and is not displaced much, the pile survives. If the pile survives but not the ATON, replacing just the ATON is much simpler and cheaper than replacing both the pile and the ATON.
The prior art has made many attempts to design a pile that will withstand repeated strikings by marine traffic and remain functional However, all of these designs suffer from drawbacks such as being excessively complex or expensive; some have external cables, etc. which degrade over time and repeated minor strikings to the point where they will not function; and others fail for some other reason. For these reasons ATON support piles remain for the most part wooden posts driven into the bottom, and therefore need to be replaced each time they are struck.